Gen. Robert B. Neller, the 37th Commandant of the Marine Corps, said the corps has been effectively organized, equipped and trained to battle an insurgency, “but the next fight is not going to be like that. It’s going to be different.”

The next war might be in space, cyberspace or elsewhere, he said, adding that the Marines may have to fight to the front in a future conflict. “The game has changed,” he said. “I think everybody realizes that.”